war, laws of

Development

In the Middle Ages the ideals of knighthood restrained some cruelties in warfare, but systematic legal codes did not appear until the 17th cent. The great work of Grotius, De jure belli ac pacis [on the laws of war and peace] (1625) and the works of Vattel had much influence in introducing humane practices. Detailed international treaties governing war are mostly a product of the 19th and 20th cent. The Declaration of Paris (1856; see Paris, Declaration of), the accords concluded at the Hague Conferences (1899, 1907), and the Geneva Conventions (1864, 1906, 1929, 1949) are the main bodies of formulated law.